Hi Drew, I've got tracks and jack mounted on the roof rack.
I recently made a clamp for a BBQ gas bottle to attach to the ladder. My ladder is steel with flat rather than tubular sides, so it has some flex, which can either save it, or make it flex back & forth too much and crack through.
I wasn't sure how it would last, but to strengthen it, I drilled a rivet out on the body capping and put in a stainless bolt that pokes out. I secured the bolt with a nylock, then a clamp from the mounting system for the gas bottle secures to the bolt with a wingnut and that gives it some extra stabilisation. The product test was 12,000km with about 2,000km of off-road, including the Bungles & Tanami tracks. It all survived well.
So I think the idea of securing a ladder carrying weight over rough terrain to 3 points instead of two is worth applying to the aforementioned design.

